Thin film thermoelectric devices are typically much smaller and more fragile than comparable bulk-type thermoelectric modules. An area for a typical thin film thermoelectric device is on the order of 140 square millimeters (mm2) whereas an area of a typical bulk-type thermoelectric module is on the order of 1,600 mm2. Thin film thermoelectric devices can be disposed between heat sinks to form a thermoelectric heat exchanger. A thermal resistance of a thermal interface material between a thermoelectric device and an attached heat sink is defined as l/kA, where l is a thickness of the thermal interface material, k is a thermal conductivity of the thermal interface material, and A is an area of an interface between the thermoelectric device and the heat sink. This means that the thermal resistance of the thermal interface material between a thin film thermoelectric device and a heat sink is on the order of 10 times higher than the thermal resistance of the thermal interface material between a larger bulk-type thermoelectric module and a corresponding heat sink. For thin film thermoelectric devices and, in particular, thin film thermoelectric coolers, the higher thermal resistance of the thermal interface material results in a higher hot side temperature and requires a lower cold side temperature, which leads to higher power consumption and/or inability to cool adequately.
In addition, given their dimensions and material set, thin film thermoelectric devices cannot withstand as much mechanical loading as bulk-type thermoelectric modules. Further, thin film thermoelectric devices cannot withstand uneven mechanical loading. However, heat sinks attached to both sides of thin film thermoelectric devices tend to be quite large compared to the thin film thermoelectric devices and are often constrained in a given product. As such, it is difficult to get even, controlled loading on a thin film thermoelectric device.
Therefore, there is a need for systems and methods for minimizing the thermal resistance of the thermal interface material between thin film thermoelectric devices while also protecting the thin film thermoelectric devices from mechanical loading.